This is Part 2 of the multi-episode crossover mini-series called “Elseworlds,” which has DC Comics (and CW) costumed superheroes Arrow, the Flash, and Supergirl, among others, teaming up on a single mission. In yesterday’s The Flash, this particular mission also involved Supergirl’s cousin, a.k.a. Superman, as well as mere mortal Lois Lane, who’s already been a central figure in three different TV series through the ages: The Adventures of Superman, Lois & Clark